Flower and Nectar Characteristics of Nine Species of Labiatae and their influence on Honeybee Visits

SummaryThe anatomy of the nectary, the relative amount of nectar secreted, the composition of the nectar and its sugar concentration, were studied in 9 species of the family, Labiatae (Coridothymus capitatus, Melissa officinalis, Phlomis viscosa, Rosmarinus officinalis, Salvia fruticosa, S. hierosolymitana, S. judaica, Satureja thymbra, Stachys aegyptiaca). The visitng rate of the honeybees to the various species was investigated. The nectar is secreted from the asymmetrically thick, disc-like nectary, through modified stomata. These occur on the thicker side of the nectary only. There is a correlation between the volume of the nectary and the amount of nectar secreted. The larger the nectary, the more nectar it secretes. No correlation was found between the type of vascular tissue (phloem, xylem) and the sugar concentration in the nectar, Rosmarinus officinalis and Coridothymus capitatus were the species most frequently visited by honeybees. The quantitative relationship between sucrose, glucose and fruc...